#include <u.h>#include <libc.h>#include <thread.h>#include "threadimpl.h" /* first argument goes in a register; simplest just to ignore it */static voidlauncherarm64(int, void (*f)(void *arg), void *arg){	(*f)(arg);	threadexits(nil);} void_threadinitstack(Thread *t, void (*f)(void*), void *arg){	uintptr *tos; 	tos = (uintptr*)&t->stk[t->stksize&~15];	*--tos = (uintptr)arg;	*--tos = (uintptr)f;	*--tos = 0;	/* first arg to launcherarm64 */	*--tos = 0;	/* place to store return PC */ 	t->sched[JMPBUFPC] = (uintptr)launcherarm64+JMPBUFDPC;	t->sched[JMPBUFSP] = (uintptr)tos;}